package com.example.musicapp.utils;

import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.Log;

import com.example.musicapp.storage.db.MyDatabaseHelper;

import java.io.FileDescriptor;

public class ImageResizer {
    private static final String TAG = "ImageResizer";

    private ImageResizer() {
    }
    private static volatile ImageResizer sImageResizer;
    /**
     * 双重锁判定单例
     * @return 返回单例对象
     */
    public static ImageResizer getInstance() {
        if (sImageResizer == null) {
            synchronized (ImageResizer.class) {
                if (sImageResizer == null) {
                    sImageResizer = new ImageResizer();
                }
            }
        }
        return sImageResizer;
    }

    public Bitmap decodeSampledBitmapFromResource(Resources res,
            int resId, int reqWidth, int reqHeight) {
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeResource(res, resId, options);

        options.inSampleSize = calculateInSampleSize(options, reqWidth,
                reqHeight);

        options.inJustDecodeBounds = false;
        return BitmapFactory.decodeResource(res, resId, options);
    }

    public Bitmap decodeSampledBitmapFromFileDescriptor(FileDescriptor fd, int reqWidth, int reqHeight) {
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeFileDescriptor(fd, null, options);

        options.inSampleSize = calculateInSampleSize(options, reqWidth,
                reqHeight);

        options.inJustDecodeBounds = false;
        return BitmapFactory.decodeFileDescriptor(fd, null, options);
    }

    public int calculateInSampleSize(BitmapFactory.Options options,
            int reqWidth, int reqHeight) {
        if (reqWidth == 0 || reqHeight == 0) {
            return 1;
        }

        final int height = options.outHeight;
        final int width = options.outWidth;
        Log.d(TAG, "origin, w= " + width + " h=" + height);
        int inSampleSize = 1;

        if (height > reqHeight || width > reqWidth) {
            final int halfHeight = height / 2;
            final int halfWidth = width / 2;

            while ((halfHeight / inSampleSize) >= reqHeight
                    && (halfWidth / inSampleSize) >= reqWidth) {
                inSampleSize *= 2;
            }
        }

        Log.d(TAG, "sampleSize:" + inSampleSize);
        return inSampleSize;
    }
}
